1. Field of the Invention
This invention relates to an air conditioning condenser for use in an automobile.
2. Description of the Prior Art
Serpentine air conditioning condensers of the type used in automobiles, in the past, have been constructed using a single flow tube having a circular cross-sectional area through which the cooling fluid to be condensed was passed. The tube had to be of a sufficient length to provide enough surface area for heat to be effectively transferred from the cooling fluid to the surrounding air as the cooling fluid flowed through the condenser. To minimize the amount of space the condenser occupied, the flow tube would usually have several turns or bends so that portions of the tube were parallel with one another.
Air conditioning condensers employing the single serpentine flow tube had severe limitations. Because the cooling fluid had to pass through a single tube, the tube had to have a fairly large cross-sectional area to maintain an acceptable pressure drop through the heat exchanger. This required that the flow tube be quite long to provide enough surface area for effective heat transfer to occur.
Multi-pass, parallel flow air conditioning condensers have overcome some of the limitations of the single tube condensers. These parallel flow air conditioning condensers cause the cooling fluid to be cooled more efficiently within a smaller amount of space. Typically, the parallel flow condensers consist of a set of header pipes which are connected to a set of parallel tubes. Baffles are provided in each header pipe to direct the fluid through banks of several of the parallel cross flow tubes. Because the fluid passes through several tubes instead of a single tube, the cross flow tubes can have a much smaller cross-sectional area while providing a much larger amount of surface area for heat transfer.
Cross flow tubes of the type described are usually substantially flat, extruded aluminum tubes. These tubes are usually arranged so that cooling air flows across the width of the tube from one edge to another. The most efficient cooling takes place at the edges of the tube where there is more surface area contact with the surrounding air. This is especially true along the lead edge of the tube where the air first contacts the tube.
The cross flow tubes used for the parallel flow condensers often have partitions or webs which are formed along the length of the tube and divide the interior of each tube into several longitudinal flow passages through which the cooling fluid flows. The partitions or webs strengthen the tubes, which could otherwise be damaged by the extreme high pressure of the cooling fluid. Because these partitions or webs extend longitudinally along the length of the tube, fluid flowing through interior passages of the tube is not cooled as effectively as the fluid flowing along the leading edges where the air first contacts the tube.